The killing of al-Qaida leader Osama bin Laden puts his Egyptian deputy Ayman al-Zawahiri in position to become the new figurehead of the global terror network and the world’s most wanted man.

Experts have long considered Zawahiri to be al-Qaida’s main strategist and operational organizer, who kept the terror network together after U.S.-led forces pushed it out of its main Afghan bases in 2001. Bin Laden has largely been seen as a charismatic figurehead who brought money and recruits to al-Qaida.

The 59-year old Egyptian surgeon was born in Cairo to a wealthy family of doctors and scholars and became involved with radical Islam as a teenager. While earning a medical degree, he helped to form the Egyptian Islamic Jihad militant group.

Zawahiri traveled to Pakistan for the first time in 1980, working with the Red Crescent Society in the city of Peshawar to provide medical treatment to Afghans wounded in fighting with Soviet troops occupying neighboring Afghanistan. He also made his trips into Afghanistan that year.

Egyptian authorities later jailed Zawahiri for three years as part of a crackdown on militants blamed for the 1981 assassination of President Anwar Sadat. After his release in 1984, Zawahiri returned to Peshawar to support the Afghan insurgency against the Soviets and formed a bond with bin Laden, serving as his personal doctor.

In 1998, Zawahiri formed an alliance with bin Laden, becoming his deputy. The United States accuses the Egyptian of helping to organize the bombings of U.S. embassies in Kenya and Tanzania later that year.

Zawahiri also is suspected of playing a major role in the September 11th, 2001 terrorist attacks on the United States, for which al-Qaida claimed responsibility from its base in Afghanistan. He went into hiding with bin Laden when U.S.-led forces invaded Afghanistan weeks later, ousting the country’s Taliban militant rulers, who had sheltered the terror network.

A U.S. air strike killed the Egyptian’s wife and at least two of his children in southern Afghanistan’s Kandahar province in December 2001.

Zawahiri proceeded to rebuild al-Qaida in the lawless tribal regions of the Afghan-Pakistani border and became the new face of the terror network, releasing videos and audiotapes taunting the United States as bin Laden faded from view.

In some videos, the bearded Zawahiri could be seen jabbing his finger and staring from behind heavy-rimmed glasses. He survived a U.S. air strike that targeted him in a Pakistani tribal region in January 2006 and remains at large. The United States has a $25 million reward for information leading to his arrest or conviction. voa